The first improvement upon the printing-press was made by the celebrated earl of Stanhope. lie constructed the press of iron, and that of a size sufficient to print the whole surface of a sheet, and he applied such a combined action of levers to the screw as to make the pull a great deal less laborious to the pressman, the mechanism altogether being such as to permit much more rapid and efficient working. A multitude of improvements speedily succeeded that of earl Stanhope, in most of which the screw was dismissed, the pressure being generally effected by levers, or by the simple and efficient principle of straightening a joint. Among those which have gained a large share of approbation may be mentioned the Columbian press, which is of American invention. This press was brought to Great Britain in 1818 by Mr. George Clymer of Philadelphia, and patented. The pressing-power in this instance is procured by a long bar or handle acting upon a-combination of exceedingly powerful levers above the platten, the return of the handle or levers being effected by means of counterpoises or weights. For ease and facilitymf pug this press is preferred by most workmen; and certainly the powerful command which the leverage enables the workman to exercise, is favorable to delicacy and exactness of printing—his arm feeling, as it were, through the series of levers to the very face of the types. In the present day, the old wooden press of Blaeu is entirely discarded from use.
To secure good printing, the following points are essential: 1. The types, carefully set, fixed with precision in forms, rendered level all over, so that all parts may be pressed alike, and the whole properly cleaned by a wash of potash lye. 2. A uniform inking of the surface, to give uniformity of color. 3. The paper clamped equably, neither too much nor too little, so as to take an impression easily and evenly. 4. An equable, firm, and smart pressure, and with that degree of steadiness iu the mechanism that the sheet shall touch and leave the types without shaking and blurring. 5. Care in adjusting the pointers (or gauge), so that perfect register may be secured in printing the second side. 6. Such frequency in or under-sheets on the tympan, that the first side shall not get dirtied by off-setting when printing the second side. 7. The laying of small patches on the tympan, where, from any inequality, it seems necessary to bring up the pressing surface to a thorough equality. A regard to all these circumstances constitutes the duty of a pressman. Bad printing is usually a result of old and worn types, want of proper cleaning, and an inferior kind of ink.
Printing by hhnd-presses of an improved kind continues to be used in the case of limited impressions, or where extra care and elegance in typography are required; also where machinery is unattainable; but in general circumstances, and more particularly to meet the demand for popular reading, urinting is now executed by one or other of the varieties of cylinder-presses, moved by steam-power. Attempts have indeed been made
to introduce flat-pressure machines, by which as many as 700 sides can be printed per hour; but these, though possessing the advantage of superseding severe bodily labor, and demanding only the services of a to lay on, and another to take off the sheets, have never become common. More success, as regards flat-pressure machines, has been attained in the United States, where much fine work is provided by a clever adaptation of this kind, particularly in New York. Boston, and Philadelphia. No fiat pressure. however, can compete, in point of speed, with the pressure which is communicated Ly revolving iron cylinders.
Cylinder-printing is the great modern fact in the history of the art, progress in which department has been facilitated by the invention of inking rollers made of a certain composition, to supersede the old process of inking by stuffed balls (see Rom.Ens). In 1700, Mr. Nicholson, the editor of the Philosophical Journal, procured a patent for certain improvements in printing., which patent embodies almost every principle since so successfully applied to printing-machines; and although he did not carry his views into practical effect, little has been left for subsequent engineers to do, but to apply, in the most judicious manner, the principles he laid down in his patent. Whether Mr. Nicholson's ideas were known to Mr. Kiimig, a German, is now uncertain; but to him is clue the distinguished merit of carrying steam-printing first into effect. Arriving in London about 1804, he first projected improvements on the common press; but, after a while, he turned his attention to eylinder-printin gr. The first result of his experiments was a small machine, in which the two leading features of Nicholson's invention were embraced (the cylinders and the inking-rollers), which he exhibited to Mr. Walter, proprietor of the Times newspaper; and on showing what further improvements were contemplated, an agreement was entered into for the erection of two machines for printing that journal. Accordingly, on Nov. 28, 1814, the public were apprised that the number of the Times of that date was the first ever printed by machinery, steam propelled. At this period, but few persons knew of any attempts going on for the attainment of this object; whilst among those connected with printing, it had often been talked of, but treated as chimerical.